Hypochlorite and hypochlorous acid solutions are known to be highly effective antimicrobial agents. However, their potential as antimicrobial agents have been under-exploited because their highly reactive, chemically aggressive, and unstable nature makes them difficult to use. For example, hypochlorite and hypochlorous acid solutions are generally not suitable as ingredients in antimicrobial cleaning solutions because of their reactive and unstable nature. Consequently, efforts have been made to develop more stable and user-friendly forms of hypochlorite and hypochlorous acid solutions.
Sometimes, hypochlorite and hypochlorous acid solutions are stabilized by the generation of various N-chloro compounds by reaction of hypochlorite sources with various amines and amides.
For example, a process for stabilizing alkali-metal hypochlorite solutions by using benzene sulfonamide, benzene N-sodium sulfonamide, or p-toluene sulfonamide as the stabilizing agent is known. Aqueous stabilized hypochlorite solutions, such as N-chlorosulfamate solutions, are also known. More specifically, stabilization of chlorine solutions (e.g., yielding the hypochlorite ion) with the sulfamate ion in concentrations as low as 0.4 ppm with total available chlorine sufficient to give free available chlorine in a lethal range of at least 0.2 ppm is known. The resulting stabilized chlorine solution may be used in cooling towers.
It is also known to bleach cellulose materials, particularly wood pulps, with an agent such as N-chlorosulfamic acid and N,N-dichlorosulfamic acid derived from an inorganic hypochlorite and sulfamic acid. The use of sulfamic acid with hypochlorite is said to reduce the amount of hypochlorite required to attain a predetermined level of bleaching by 40–80% of that otherwise required. It also allows the bleaching operation to be carried out at a pH substantially lower than normal and yields a pulp of materially higher viscosity and strength.
It is also known to make stable aqueous solutions of N-halo compounds in which the N-halo compounds are formed by mixing an N-hydrogen compound (e.g., sulfamic acid, sulfamide, dimethylhydantoin) with NaOCl or NaBr. The aqueous system is stabilized by including a buffer that maintains the pH of the system between 4 and 11. A similar process of preparing stable solutions of N-halo compounds entails reacting an N-hydrogen compound, e.g. sulfamic acid, in the presence of hydroxides.
Stabilized hypochlorite solutions such as N-chlorosulfamate solutions are also known to possess antimicrobial activity.
N-chlorosulfamate solutions, however, have not been considered highly desirable as biocidal or disinfecting agents in applications that involve human contact, for example, in swimming pools. Disinfecting a swimming pool requires rapid microbial elimination, which is usually not performed by N-chlorosulfamate because N-chlorosulfamate has a weak antimicrobial activity relative to other hypochlorite-containing compounds such as NaOCl, HOCl, chlorinated isocyanuric acids (e.g., trichloroisocyanuric acid and sodium dichloroisocyanurate), and chlorinated hydantoins (e.g., 1,3-dichloro-5,5-dimethylhydantoin).
Certain N-hydrogen compounds (e.g., dimethylhydantoin, methylhydantoin, cyanuric acid, succinimide, and glycoluril) and their chlorinated derivatives can dramatically improve the bactericidal efficacy of hypochlorite solutions in pulp slurries, presumably by increasing the lifespan of the active chlorine. According to some sources, the addition of dimethylhydantoin to sodium hypochlorite solutions enhances the biocidal activity of sodium hypochlorite, and the activity of hydantoins is greater than that of sulfamic acid and similar to cyanuric acid.
One or more organic dopant(s) may be added to a solution of N-chlorosulfamate to improve the antimicrobial efficacy of the solution. The organic dopants include 5,5-dialkyl hydantoins, arylsulfonamides, and succinimides.
A stabilized N-chlorosulfamate may be produced from a composition containing a peroxygen compound and a halogen source such as NaCl and N-sulfamate. It is also known to react chlorine gas with a solution containing N-succinimide to produce a high purity N-chlorosuccinimide for germicidal or chemical reaction applications.
Succinimide, isocyanurate, and hydantoins are effective stabilizers of halogens like chlorine and bromine. However, the halogenated versions of these compounds are susceptible to increased decomposition when combined with other agents such as surfactants, oxidizers, alkalis, dispersants and the like. Therefore, their shelf life is limited, and in cases where contaminants contact these agents, there is even a risk of rapid decomposition and fire.
A storable, stable composition that provides the effective antimicrobial benefits of the halogenated agents is desired.